This invention relates to electric discharge lamps that have an integral ballast, and more particularly to lowering the ballast temperature of a universal position lamp.
The mass-produced incandescent lamp is relatively inexpensive but is inefficient, and the increasing cost of electrical energy has led to a re-evaluation of them relative to other types of long life, high efficiency lamps. If the cost of operating incandescent lamps is considered, along with their relatively short lifetimes, incandescent lamps may be uneconomical in certain situations. A number of different kinds of lamps have been suggested to fill the need for an efficient and long lasting lamp.
One candidate to replace the incandescent bulb is the HALARC.RTM. lamp from the General Electric Company, Cleveland, Ohio, one configuration of which is illustrated. The light output is provided mainly by the visible electromagnetic radiation in the miniature arc tube; an electronic ballast in the lamp itself limits the current and supplies starting and running voltage. The first generation of the HALARC lamp is designed only for base down usage. The natural convection inside the glass envelope containing the arc tube does not flow toward the ballast housing, and therefore the temperature of the electronic board is not excessive and it is under normal operating condition. In the base up position of the lamp, the ballast temperature is far beyond the limit of operating temperature of a reliable electronic system.
The second generation HALARC lamp is a universal position bulb installed either base down or base up. One of the most critical problems is the excessive ballast temperature in the base up mounting. According to ballast designers, every 10.degree. C. decrease of the ballast temperature will double its lifetime. An economical thermal improvement concept which can significantly reduce the temperature of the electronics package will impact development of the universal position miniature arc lamp.